The present technology relates to an optical element that is used in a collector for collecting the sunlight or artificial light. The present technology also relates to a method of manufacturing the optical element, an illumination device, a window member, and a fitting.
Recently, sunlight collectors have been developed with the view of reducing electric power consumed by lighting apparatuses, when they are used in the daytime, by taking in the sunlight incoming from the sky toward the ceiling inside a house or a building. Various types of structures, e.g., a light duct, a louver, and a window blind (shade), are employed as related-art sunlight collectors.
For example, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2002-526906 describes an optical component for causing incident light to be directionally output by utilizing total reflection generated at a gap (space) that is formed inside an optically transparent body. Japanese Unexamined Patent Application Publication No. 2009-266794 describes a sunlight illuminator including a plurality of bar-shaped element members made of a transparent material, and a support for supporting the plural element members such that the element members are arrayed parallel to each other. In the sunlight illuminator, the sunlight incoming from the outdoor side is reflected by reflecting surfaces of the element members to be introduced toward the ceiling in the indoor side. Japanese Patent No. 3513531 describes a sunlight collector for causing incident light to be diffusively output through bar-like members, which are arrayed on the surface of a transparent body in the form of a flat plate. Japanese Unexamined Patent Application Publication No. 2001-503190 describes an optical guide plate in which, in a plate made of a transparent plastic having a first refractive index, a plurality of thin belt-like members made of a plastic having a second refractive index are inserted such that incident light is directionally output due to the difference in refractive index between the plate and the belt-like members.